Aqueous polyurethane preparations

ABSTRACT

Aqueous polyurethane formulations, their use and substrates which are coated with such formulations are described.

The polyurethane dispersions used for coating substrates, e.g. wood,metal, plastic, textiles or leather, generally give highly glossypolymer films.

In some applications, for example in the coating of automotive leathersand upholstery leathers, however, coatings having very low gloss arerequired. This low gloss should not change even as a result of rubbing,as occurs during use, i.e. the coating should be polishable to a verysmall extent. Moreover, the coating should not cause any change in thehue of the substrate; for example, the coating should not make a blackleather appear gray.

DE-A1 4 016 713 describes mixtures of polymer dispersions which arefilm-forming below 70° C. with polyurethane-polyurea dispersions whichare not film-forming below 70° C. for the production of dull coatings. Adisadvantage of these mixtures is that two different dispersions have tobe provided for their preparation, which means greater expense withregard to synthesis.

DE-A1 4 017 525 describes aqueous polyurethane formulations whichcontain a polyurethane which is obtained from at least one diisocyanatehaving no lateral groups and at least one diisocyanate having at leastone lateral group. However, the coatings which are obtained with thesedispersions no longer meet present day requirements with regard topolishability. Furthermore, the dispersions thus obtainable havestability problems.

It is an object of the present invention to provide polyurethanedispersions which meet the following requirements:

-   -   coatings obtained therefrom should have very low gloss.    -   the gloss should not change substantially as a result of rubbing        (no polishability).    -   the coating should not substantially change the hue of the        substrate.    -   said properties should be obtained by using a single        polyurethane dispersion.    -   leathers treated with the polyurethane dispersions should have        good mechanical properties.

We have found that this object is achieved by aqueous polyurethaneformulations comprising from 10 to 60% by weight of at least onepolyurethane A which is composed of

-   a) at least one organic isocyanate having no lateral alkyl groups    [monomers I],-   b) if required, at least one organic isocyanate having at least one    lateral alkyl group [monomers II],-   c) at least one dihydric or polyhydric alcohol having a number    average molecular weight of from 400 to 6 000 [monomers III],-   d) at least one dihydric or polyhydric alcohol having a number    average molecular weight of from 62 to 399 [monomers IV],-   e) at least one carboxylic acid having at least one hydroxyl group    [monomers V],-   f) no or one or more polyamines having at least two >N—H groups    [monomers VI],-   g) no or one or more compounds having at least one alcoholic OH    group and at least one >N—H group [monomers VII] and-   h) no or one or more monohydric polyetheralcohols [monomers VIII],    with the proviso that the amounts of the incorporated monomers I to    VIII are such that the (—OH+>N—H)/NCO equivalent ratios for the    incorporated

monomers III/monomers I + II are from 0.1 to 0.75, monomers IV/monomersI + II are from 0.2 to 0.8, monomers V/monomers I + II are from 0.05 to0.5, monomers VI/monomers I + II are from 0 to 0.4, monomersVII/monomers I + II are from 0 to 0.4, monomers VIII/monomers I + II arefrom 0 to 0.2 andthose for the sum of the monomers III to VIII/monomers (I+II) are from0.80 to 1.25, the total amount of monomers I and monomers II containsfrom 50 to 100 mol % of monomers I and from 50 to 2 000 mmol of thecarboxyl groups of the incorporated monomers V per kilogram ofpolyurethane A are present in neutralized form in the aqueousformulation.

The present invention also relates to a process for the preparation ofthese formulations as coating materials, in particular for coatingswhich have low gloss and low polishability.

Suitable monomers I whose organic skeleton has no lateral alkyl groupare mono-, di- or polyisocyanates or mixtures thereof, preferably thealiphatic diisocyanates hexamethylene diisocyanate and4,4′-diisocyanatodicyclohexylmethane.

Suitable monomers II whose organic skeleton has at least one lateralalkyl group are mono-, di- or polyisocyanates or mixtures thereof,preferably isocyanates such as trimethylhexane diisocyanate,1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (IPDI),2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, tetramethylxylylenediisocyanates, and polyisocyanates derived therefrom and havingcarbodiimide, allophanate, isocyanurate, urethane or biuret groups.Diisocyanates are preferred, among which the aliphatic diisocyanates, inparticular 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexaneand the trimethylhexane diisocyanates are particularly preferred. Thelateral alkyl groups of the monomers II preferably contain 1 to 3 carbonatoms, particularly preferably 1 carbon atom, per lateral alkyl group.

If monoisocyanates are concomitantly used in the case of the monomers Ior II, the amount of monoisocyanates is preferably such that theycontribute in each case not more than 10 mol % of isocyanate groups tothe total amount of the isocyanate groups within the monomers I or II.Advantageously, both the monomers I and the monomers II have an averageNCO functionality of 2. Monomer mixtures I and/or II which are composedexclusively of diisocyanates are particularly advantageous. Furthermore,the total amount of monomers I and II preferably contains from 50 to100, particularly preferably from 70 to 100, very particularlypreferably from more than 90 up to and including 100, in particular from95 to 100, exceptionally preferably 100, mol % of monomers I.

Suitable monomers III are in particular dihydric or polyhydricpolyesterpolyols and polyetherpolyols, the dihydric ones beingpreferred. Particularly suitable polyesterpolyols are the conventionalreaction products of polyhydric alcohols with polybasic carboxylicacids, the alcoholic component being used in excess. The polybasiccarboxylic acids may be aliphatic, cycloaliphatic, aromatic,heterocyclic or ethylenically unsaturated and, if required, may carryhalogen atoms as substituents. Instead of the polybasic carboxylicacids, their anhydrides may also be esterified. Examples of suitablepolybasic starting carboxylic acids are succinic acid, adipic acid,sebacic acid, phthalic acid, isophthalic acid, trimellitic acid,phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalicanhydride, tetrachlorophthalic anhydride,endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleicacid, maleic anhydride or fumaric acid. The following may be mentionedas polyhydric alcohols to be used in excess:

1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, 1,4-butenediol, 1,4-butynediol,1,5-pentanediol and its positional isomers, 1,6-hexanediol,1,8-octanediol, 1,4-bishydroxymethylcyclohexane,2,2-bis(4-hydroxycyclohexyl)propane, 2-methyl-1,3-propanediol, glycerol,trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol,1,2,4-butanetriol, diethylene glycol, triethylene glycol, tetraethyleneglycol, polyethylene glycol having a molar mass of from 378 to 900,preferably from 378 to 678, poly-1,2-propylene glycol orpoly-1,3-propanediol having a molar mass of from 134 to 1 178,preferably from 134 to 888, polytetrahydrofuran having a molar mass offrom 162 to 2 000, preferably from 378 to 1 458, particularly preferablyfrom 378 to 678.

Polyesterpolyols obtained from diols and dicarboxylic acids arepreferred. Other suitable polyesterpolyols are the adducts of lactonesor lactone mixtures with dihydric alcohols used as initiator molecules.Examples of preferred lactones are ε-caprolactone, β-propiolactone,γ-butyrolactone and methyl-ε-caprolactone.

Suitable initiator molecules are in particular the low molecular weightdihydric alcohols mentioned above as components for thepolyesterpolyols.

Polyesters obtained from hydroxycarboxylic acids are of course alsosuitable as monomers III. Furthermore, polycarbonates, as obtainable,for example, from phosgene or diphenyl carbonate and an excess of thelow molecular weight dihydric alcohols mentioned as components for thepolyesterpolyols, are also monomers III suitable as polyesters.

Preferred monomers III suitable as polyetherpolyols are polyetherdiols,as obtainable, for example, by boron trifluoride-catalyzed linkage ofethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran,styrene oxide or epichlorohydrin with themselves or with one another, orby an addition reaction of these compounds, individually or as amixture, with initiator components having reactive hydrogen atoms, suchas water, polyhydric alcohols or amines, such as 1,2-ethanediol,1,3-propanediol, 1,2- or 2,2-bis(4-hydroxyphenyl)propane or aniline.Furthermore, polyether-1,3-diols, for example trimethylolpropane whichis alkoxylated at an OH group and whose alkylene oxide chain isterminated by an alkyl radical of 1 to 18 carbon atoms, are preferablyused as monomers III.

Monomers IV may be dihydric or polyhydric alcohols, among which thedihydric ones are preferred.

Suitable monomers IV include the low molecular weight polyols mentionedas components for the polyesterpolyols III and polyhydric alcohols, suchas trimethylolbutane, trimethylolpropane, trimethylolethane,neopentylglycol, neopentylglycol hydroxypivalate, pentaerythritol,2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol,2-ethyl-1,3-hexanediol, glycerol, ditrimethylolpropane,dipentaerythritol, hydroquinone, bisphenol A, bisphenol F, bisphenol B,bisphenol S, 2,2-bis(4-hydroxycyclohexyl)propane, 1,1-, 1,2-, 1,3- and1,4-cyclohexanedimethanol, 1,2-, 1,3- or 1,4-cyclohexanediol or sugaralcohols, such as sorbitol, mannitol, diglycerol, threitol, erythritol,adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol),maltitol or isomaltitol. Preferably linear 1,ω-dihydroxyalkanes,particularly preferably 1,4-butanediol and 1,6-hexanediol, areincorporated into polyurethane A. Particularly preferably, both themonomers III and the monomers IV consist exclusively of dihydricalcohols. Advantageously, the amounts of the monomers III and IVincorporated into the at least one polyurethane A are such that themolar ratio of their alcoholic —OH groups (IV:III) is from 1 to 8,preferably from 2 to 6.

Carboxylic acids having at least one hydroxyl group (—OH) [monomer V]are those compounds which contain at least one carboxyl function(—COOH), preferably from one to three, particularly preferably one ortwo, carboxyl functions (—COOH), very particularly preferably onecarboxyl function (—COOH), or the anionic forms thereof, with which anydesired opposite ion or a plurality thereof may be associated, e.g. Li⁺,Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺ or Ba²⁺. Furthermore, the ammonium ions orquaternary ammonium ions derived from ammonia or amines, in particulartertiary amines, e.g. ammonium, methylammonium, dimethylammonium,trimethylammonium, ethylammonium, diethylammonium, triethylammonium,tributylammonium, diisopropylethylammonium, benzyldimethylammonium,monoethanolammonium, diethanolammonium, triethanolammonium,hydroxyethyldimethylammonium, hydroxyethyldiethylammonium,monopropanolammonium, dipropanolammonium, tripropanolammonium,piperidinium, piperazinium, N,N′-dimethylpiperazinium, morpholinium,pyridinium, tetramethylammonium, triethylmethylammonium,2-hydroxyethyltrimethylammonium, bis(2-hydroxyethyl)dimethylammonium ortris(2-hydroxyethyl)methylammonium, may be associated as an oppositeion.

A preferred opposite ion is ammonium. If a plurality of differentopposite ions are present, the amount of ammonium ions among these ispreferably from 50 to 100, particularly preferably 75–100, veryparticularly preferably 90–100, in particular 100, mol %.

The carboxylic acids having at least one hydroxyl group may bealiphatic, cycloaliphatic or aromatic, branched or straight-chain andunsubstituted or substituted.

Particularly preferred monomers V are of 2 to 6, very particularlypreferably 3 to 5, in particular 4 or 5, carbon atoms.

Examples of monomers V are hydroxyacetic acid, tartaric acid, lacticacid, 3-hydroxypropionic acid, dimethylolpropionic acid,dimethylolbutyric acid, trimethylolacetic acid, hydroxypivalic acid orsugar acids, such as gluconic acid, glucaric acid, glucuronic acid,galacturonic acid or mucic acid (galactaric acid), preferably lacticacid, dimethylolpropionic acid, dimethylolbutyric acid,trimethylolacetic acid, hydroxypivalic acid and glucuronic acid,particularly preferably lactic acid and dimethylolpropionic acid, veryparticularly preferably dimethylolpropionic acid.

The monomers V may also be used in the form of a mixture.

The novel polyurethane formulations preferably contain polyurethanes Ain which from 70 to 1 000, particularly preferably from 100 to 700, mmolof the carboxyl groups of the incorporated monomers V per kilogram ofpolyurethane A are present in ionized form, i.e. in the anionic form, inthe aqueous formulation.

The monomers VI preferably have a molecular weight of from 32 to 500,particularly preferably from 60 to 300. They are exclusively polyamineswhich have no tertiary amino groups. Examples of suitable monomers VIare diamines, such as 1,2-diaminoethane, 1,6-diaminohexane, piperazine,2,5-dimethylpiperazine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane(IPDA), 4,4′-di(aminocyclohexyl)methane, 1,4-diaminocyclohexane, 1,2-and 1,3-diaminopropane, hydrazine, hydrazine hydrate, triamines, such asdiethylenetriamine, or tetramines, such asN,N-bis(3-aminopropyl)-1,4-diaminobutane. However, other suitablemonomers VI are ketimines, as described in DE-B 27 25 589, ketazines,such as those of DE-B 28 11 148 and of U.S. Pat. No. 4,269,748, aminesalts, such as those in U.S. Pat. No. 4,292,226, or oxazolidines, asdescribed in DE-B 27 32 131 and U.S. Pat. No. 4,192,937. These aremasked polyamines from which the corresponding polyamines are liberatedas intermediates in the presence of water.

Preferably used monomers VI are ethylenediamine,1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (IPDA) and4,4′-di(aminocyclohexyl)methane, and1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (IPDA) is particularlypreferably used.

According to the invention, the (—OH+>N—H)/NCO equivalent ratio for themonomers VI/(I+II) used is from 0 to 0.4, preferably from 0 to 0.2,particularly preferably from 0.02 to 0.2.

Particularly suitable monomers VII are aminoalcohols, such asethanolamine, isopropanolamine, methylethanolamine andaminoethoxyethanol.

The monomers VIII preferably have a number average molecular weight offrom 500 to 10 000, particularly preferably from 1 000 to 5 000. Theyare usually obtainable by alkoxylation of low molecular weightmonofunctional initiator molecules, such as methanol, ethanol orn-butanol, the alkoxylating agent used preferably being ethylene oxideor a mixture of ethylene oxide with other alkylene oxides, in particularpropylene oxide. In the case of alkoxylation with alkylene oxidemixtures, these advantageously contain at least 40, particularlyadvantageously at least 65, mol % of ethylene oxide. The amount of themonomers VIII should expediently not exceed 10% by weight, based on thetotal weight of the incorporated monomers.

Further examples of monomers I to VIII suitable for the synthesis of thepolyurethanes A are described, for example, in-High Polymers, Vol. XVI,Polyurethanes, Chemistry and Technology, Interscience Publishers, NewYork, Vol. 1, 1962, pages 32 to 42, pages 44 to 54, and Vol. II, 1964,pages 5 to 6 and pages 198 to 199. The polyurethanes A preferablycontain, as incorporated units, only those monomers I to VIII which havetwo isocyanate groups or two groups reactive with isocyanate groups. Themonomers I to VIII are advantageously incorporated into the at least onepolyurethane A in amounts such that the total number of isocyanategroups is matched by a roughly equivalent total number of hydroxyl andamino groups reactive with isocyanate groups. The equivalent ratio ispreferably from 0.9 to 1.11, particularly preferably from 0.95 to 1.05.

The novel aqueous polyurethane formulations are expediently prepared byreacting the monomers I to V and, if required, the monomers VII and VIIIin the melt or in the presence of an inert, water-miscible solvent, suchas acetone, tetrahydrofuran, butanone, diethyl ketone, a cyclic oropen-chain carbonate or N-methylpyrrolidone, at from 20 to 160° C.,preferably from 50 to 100° C., the duration of the reaction usuallybeing from 2 to 10 hours. The reaction can be accelerated by thepresence of substances which are catalytically active in a manner knownper se, such as dibutyltin dilaurate, tin(II) octanoate or1,4-diazabicyclo[2.2.2]octane, usually in amounts of from 10 to 100 ppm,based on the solvent-free reaction mixture. Thereafter, dilution iseffected, if required, with a water-miscible solvent, ionogenic groupsof the monomers V are, if required, ionized by neutralization, water isadded and, if required, the monomers VI are stirred in. Any organicsolvents present are then usually distilled off, and it is for thisreason that solvents whose boiling point is below the boiling point ofwater are preferred. If monomers VI are also incorporated into thepolyurethane A, they are added to the aqueous reaction mixturecontaining the polyurethane composed of the remaining monomerspreferably by stirring in at from 20 to 50° C. If required, the monomersVI can also be added before the dispersing with water.

The amount of water added is usually such that the novel aqueouspolyurethane formulations have a solids content of from 10 to 80% byweight. Apart from typical components insoluble in N,N-dimethylformamide(DMF), the polyurethanes contained in the formulations generally have aK value of from 20 to 80 in DMF. The K value is a relative viscositynumber which is determined analogously to DIN 53 726 at 23° C. Itcomprises the flow rate of a 1% strength by weight solution of-thepolyurethane in DMF, relative to the flow rate of pure DMF, andcharacterizes the average molecular weight of the polyurethane.

In the preparation of aqueous polyurethane dispersions, the additionreaction, i.e. the reaction of the individual monomers with one another,is frequently carried out with the use of catalysts. Organic compoundsof tin, for example dibutyltin dilaurate or tin(II) octanoate, haveproven particularly useful here. However, it is known that such organiccompounds of tin have, inter alia, high toxicity and, owing to theirpoor degradability, accumulate in the environment in an undesiredmanner. Although the diorganyl compounds of tin which are usually usedare less hazardous than the triorganyl compounds of tin, commercialpreparations of diorganyl compounds of tin always also contain certainamounts of triorganyl compounds of tin, owing to the specialpreparation. Alternatively, other organometallic compounds, i.e. thosehaving at least one covalent metal-carbon bond, are also used ascatalysts, for example bismuth organyls.

According to the invention, catalysis by any metal organyls ispreferably dispensed with.

The polyaddition of the abovementioned monomers for the preparation ofthe novel polyurethane formulation can be particularly preferablycarried out in the presence of cesium salts, as described in the priorGerman Patent Application with the application number 10161156.0 of12.12.2001. Preferred cesium salts are compounds in which the followinganions are used: F⁻, Cl⁻, ClO⁻, ClO₃ ⁻, ClO₄ ⁻, Br⁻, J⁻, JO₃ ⁻, CN⁻,OCN⁻, NO₂ ⁻, NO₃ ⁻, HCO₃ ⁻, CO₃ ²⁻, S²⁻, SH⁻, HSO₃ ⁻, SO₃ ²⁻, HSO₄ ⁻,SO₄ ²⁻, S₂O₂ ²⁻, S₂O₄ ²⁻, S₂O₅ ²⁻, S₂O₆ ²⁻, S₂O₇ ²⁻, S₂O₈ ²⁻, H₂PO₂ ⁻,H₂PO₄ ⁻, HPO₄ ²⁻, PO₄ ³⁻, P₂O₇ ⁴⁻, (OC_(n)H_(2n+1))⁻,(C_(n)H_(2n−1)O₂)⁻, (C_(n)H_(2n−3)O₂)⁻ and (C_(n+1)H_(2n−2)O₄)²⁻, wheren is from 1 to 20.

Particularly preferred cesium carboxylates are those in which the anionis of the formulae (C_(n)H_(2n−1)O₂)⁻ and (C_(n+1)H_(2n−2)O₄)²⁻, where nis from 1 to 20. Very particularly preferred cesium salts have, asanions, monocarboxylates of the formula (C_(n)H_(2n−1)O₂)⁻, where n isfrom 1 to 20. Formate, acetate, propionate, hexanoate and2-ethylhexanoate may be mentioned in particular here.

The cesium salts are used in amounts of from 0.01 to 10, preferably from0.05 to 2, mmol of cesium salt per kg of solvent-free batch.

The cesium salts may be added to the batch in solid form, but preferablyin dissolved form. Suitable solvents are polar, aprotic solvents orprotic solvents. In addition to water, alcohols are also particularlysuitable; polyols as otherwise used as building blocks for polyurethanesare very particularly suitable, e.g. ethane-, propane- and butanediols.The use of the cesium salts makes it possible to carry out thepolyaddition under the conventional conditions.

After the reaction to give the polymer, neutralization to theabovementioned degree of neutralization is preferably effected,analogously to the method as described in the prior German PatentApplication with application number 10127208.1 of 6.5.2001. Ammonia isparticularly suitable for this purpose.

The content of COO⁻ NH₄ ⁺ after the neutralization should be, forexample, from 50 to 2 000, preferably from 100 to 600, particularlypreferably from 200 to 500, very particularly preferably from 250 to500, mmol/kg.

After the neutralization, dispersing is then effected with water and anysolvent is distilled off. As a result of the addition of water and thesubsequent removal of the solvent by distillation, in particular thedesired solids concentration can be established.

Because of the particular choice of the raw materials and their ratios,the novel polyurethane formulations contain particles which areinsoluble in the polyurethane matrix and whose mean diameter is from 1to 20 μm, particularly preferably 2–15 μm, very particularly preferably3–100 μm, in particular from 3 to 7 μm.

Aqueous polyurethane dispersions which contain particles having largerparticle diameters are not stable and have a raw handle on leather;smaller particle diameters exhibit no matting effect.

The polyurethane dispersions may contain commercial assistants andadditives, such as blowing agents, antifoams, emulsifiers, thickeners,crosslinking agents, thixotropic agents and colorants, such as dyes andpigments.

The novel aqueous polyurethane formulations can advantageously be usedas binders for coating materials if, for technical or aesthetic reasons,coatings having reduced surface gloss are desired. Suitable substratesare textiles, leather, metal, plastic, glass, wood, paper or board, andpreferred substrates are textiles and leather, particularly preferablyleather. Remarkably, the coatings obtainable with the use of the novelaqueous polyurethane formulations as binders have high abrasionresistance, water resistance and resilience, low polishability, goodcolor depth and a pleasant, warm, soft (fatty) handle, in addition toreduced gloss. The novel aqueous polyurethane formulations can thereforeparticularly advantageously be used as binders for sealing coats onleathers which may have been pretreated with commercial bottomingagents, in particular automotive leather and upholstery leather. Thenovel aqueous formulations can be used by themselves or as a mixturewith other binders and conventional assistants. By mixing with otherbinders, for example other polyurethane dispersions, the gloss can bebrought to a desired level. Said formulations can be applied to thesearticles by atomization, spraying, casting, knife coating, impregnationor in the form of a film and then dried. The novel aqueous formulationsare expediently applied with a solids content of from 10 to 75,preferably from 20 to 65, % by weight and a viscosity of from 10 to 1500 mPa·s (measured at 20° C. and a shear rate of 250 s⁻¹).

The use of the novel aqueous polyurethane formulations as binders inbottoming coats is also possible.

The coatings obtainable with the novel polyurethane formulations havelow polishability and a pleasant, warm, soft (fatty) handle.

In this document, ppm data and percentages used are by weight, unlessstated otherwise.

EXAMPLES Comparative Example

A mixture of 394 kg of a polyesterdiol obtained from adipic acid,neopentylglycol and 1,6-hexanediol (hydroxyl number 56 according to DIN53 240), 90 kg of 1,4-butanediol, 0.1 kg of dibutyltin dilaurate, 72.5kg of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane and258.2 kg of 4,4′-diisocyanatodicyclohexylmethane was reacted for 3 hoursat 70° C. Dilution was then effected with 1 000 kg of acetone and themixture was cooled to 50° C. 48 kg of a 40% strength by weight aqueoussolution of the sodium salt of N-(2-aminoethyl)-2-aminoethanecarboxylicacid and 1 250 kg of water were then stirred in at 50° C. After removalof the acetone by distillation, an about 40% strength by weight aqueouspolyurethane formulation was obtained.

After storage for four weeks, the dispersion had a thick sediment whichcould not be homogeneously distributed again by shaking or stirring.

-   1. Preparation of a Novel Polyurethane Formulation    -   Z1:    -   In a stirred flask having a reflux condenser and thermometer,        400 g (0.20 mol) of polytetrahydrofuran having an OH number of        56, 40.2 g (0.30 mol) of dimethylolpropionic acid and 100 g of        butanone were brought to 80° C. while stirring. 168 g (1.00 mol)        of hexamethylene diisocyanate (HDI) were added to this all at        once. After 15 minutes, 47.2 g (0.40 mol) of 1,6-hexanediol        heated to 45° C. were added to the batch. After 15 minutes, 70 g        of acetone were added and stirring was carried out for a further        200 minutes at 80° C. During this procedure, the increasing        viscosity was reduced by gradually adding first a total of 200 g        of butanone and then a total of 200 g of acetone. 210 minutes        after the addition of the hexanediol, dilution was effected with        a further 500 g of acetone and the mixture was cooled to 30° C.        The NCO content of the dilute solution was determined as 0.49%        by weight (calculated: 0.49% by weight). Thereafter, 17.0 g (0.1        mol) of isophoronediamine (IPDA) were added and stirring was        carried out for 60 minutes at 30° C. After the addition of a        solution of 18 g of 25% strength aqueous ammonia in 80 g of        water, dispersion was effected by adding 1 300 g of water, and        acetone and butanone were distilled off under reduced pressure.    -   An aqueous polyurethane dispersion having a solids content of        33% was obtained.    -   Even on storage for four weeks, the dispersion had only a little        sediment, which could be readily homogeneously distributed again        by shaking or stirring.    -   A thin film applied to a microscope slide showed, under an        optical microscope, particles whose mean diameter was measured        as about 6 μm.-   2. Use of the Novel PUD as Binders for Coatings    -   a) An automotive leather crust was bottomed with a commercial        bottom consisting of 250 g of water, 150 g of Lepton® Schwarz N        (BASF AG, Ludwigshafen), 100 g of Luron® Mattierung (BASF AG,        Ludwigshafen), 50 g of Lepton® Filler CEN (BASF AG,        Ludwigshafen), 50 g of Lepton Mattierung MF (BASF AG,        Ludwigshafen), 100 g of Corialgrund® DN (BASF AG, Ludwigshafen),        250 g of Astacin® Finish PUMN TF (BASF AG, Ludwigshafen) and 50        g of Astacin® Finish PFM TF (BASF AG, Ludwigshafen) (amount        applied: 1 cross in spray application), dried, embossed at        80° C. under 200 bar for 1.5 s and milled for 3 hours.        -   A mixture of 300 g of water, 150 g of Lepton® Schwarz N            (BASF AG, Ludwigshafen), 100 g of Luron Mattierung (BASF AG,            Ludwigshafen), 50 g of Lepton® Filler CEN (BASF AG,            Ludwigshafen), 50 g of Lepton Mattierung MF (BASF AG,            Ludwigshafen), 100 g of Corialgrund® DN (BASF AG,            Ludwigshafen), 250 g of Astacin® Finish PUMN TF (BASF AG,            Ludwigshafen), 100 g of Astacin® Finish PFM TF (BASF AG,            Ludwigshafen) and 30 g of Astacin® Härter CN (BASF AG,            Ludwigshafen) was applied as a top coat by spray coating            (amount applied: 1 cross).        -   A mixture of 380 g of water, 10 g of Lepton® Schwarz N (BASF            AG, Ludwigshafen), 40 g of Lepton® Wachs WA (BASF AG,            Ludwigshafen), 60 g of Astacin® Härter CN (BASF AG,            Ludwigshafen) and 500 g of Z1 (BASF AG, Ludwigshafen), for            which the viscosity had been brought by means of Lepton®            Paste VL (BASF AG, Ludwigshafen) to an efflux time of 25 s            in a 4 mm DIN cup at 23° C. according to DIN 53211, was then            applied by spray coating (amount applied: 2 crosses,            intermediate drying and final drying at 80° C. in a drying            tunnel).        -   Rubfastness according to IUF 450 (DIN EN ISO 11640), wet            leather: no damage after 500 cycles,        -   rubfastness according to IUF 450, dry leather: no damage            after 2 000 cycles        -   swelling resistance, dry felt according to IUF 450: no            damage after 2 000 cycles        -   fastness to rubbing with gasoline according to IUF 450: no            damage and no discoloration after 10 rubs        -   flex resistance according to IUP20 (DIN EN 13334): dry            leather: no damage after 100 000 cycles        -   wet leather: no damage after 20 000 cycles        -   at −10° C.: no damage after 30 000 cycles        -   Taber Test CS 10 (1 000 g load) (DIN 53109): no damage after            1 000 cycles        -   Visual inspection showed no polishability at all after 2 000            dry rubs.    -   b) An automotive leather crust was bottomed with a commercial        bottom consisting of 350 g of water, 120 g of Lepton® Schwarz N,        200 g of Lepton® Filler CEN, 250 g of Corialgrund® BAN and 150 g        of Astacin® Finish SUSI TF (amount applied: 20 g of dry        material/m²).        -   A mixture of 157 g of water, 3 g of Lepton® Wachs WA, 18 g            of Astacin® Härter CN and 122 g of Z1 was then applied (2 g            wet/DIN A4) and dried at 80° C. for 5 minutes in a            through-circulation dryer, and the same amount of the            mixture was applied again and dried again.        -   A coated leather having the following properties was            obtained:        -   Gloss 20°:0.1 60°:0.5 85°:0.4        -   measured using a REFO 3D gloss meter from Lange, according            to the operating instructions.        -   In order to assess the polishability, the gloss of the rub            mark according to IUF 450 was measured after 2 000 cycles on            dry leather.        -   Gloss after 2 000 rubs: 60°:0.5 85°:0.6        -   As can be seen, the novel polyurethane formulation was very            suitable for coating leather, not only with regard to the            mechanical properties but also in respect of polishability.        -   Extremely matt, nonpolishable finishes having excellent            jetness can be achieved.

1. A matt finished leather coated with an aqueous polyurethaneformulation comprising from 10 to 60%, by weight, of at least onepolyurethane A, which is composed of a) at least one organic isocyanatehaving no lateral alkyl groups [monomers I], b) optionally at least oneorganic isocyanate having at least one lateral alkyl group [monomersII], c) at least one dihydric or polyhydric alcohol having a numberaverage molecular weight of from 400 to 6000 [monomers III], d) at leastone dihydric or polyhydric alcohol having a number average molecularweight of from 62 to 399 [monomers IV], e) at least one carboxylic acidhaving at least one hydroxyl group [monomers V], f) optionally one ormore polyamines having at least two >N—H groups [monomers VI], g)optionally one or more compounds having at least one alcoholic OH groupand at least one >N—H group [monomers VII] and h) optionally one or moremonohydric polyetheralcohols [monomers VIII], with the proviso that theamounts of the incorporated monomers I to VIII are such that the(—OH+>N—H)/NCO equivalent ratios for the incorporated monomersIII/monomers I+II are from 0.1 to 0.75, monomers IV/monomers I+II arefrom 0.2 to 0.8, monomers V/monomers I+II are from 0.05 to 0.5, monomersVI/monomers I+II are from 0 to 0.4, monomers VII/monomers I+II are from0 to 0.4, monomers VIII/ monomers I+II are from 0 to 0.2, and those forthe sum of the monomers III to VIII/monomers (I+II) are from 0.80 to1.25, the total amount of monomers I and monomers II contains from 50 to100 mol % of monomers I, and from 50 to 2000 mmol of the carboxyl groupsof the incorporated monomers V, per kilogram of polyurethane A, arepresent in anionic form in the aqueous formulation, and the dispersedpolyurethane particles have a particle size from 2–15 μm.
 2. A method ofmatting leather, comprising applying an aqueous polyurethane formulationcomprising from 10 to 60%, by weight, of at least one polyurethane A,which is composed of a) at least one organic isocyanate having nolateral alkyl groups [monomers I], b) optionally at least one organicisocyanate having at least one lateral alkyl group [monomers II], c) atleast one dihydric or polyhydric alcohol having a number averagemolecular weight of from 400 to 6000 [monomers III], d) at least onedihydric or polyhydric alcohol having a number average molecular weightof from 62 to 399 [monomers IV], e) at least one carboxylic acid havingat least one hydroxyl group [monomers V], f) optionally one or morepolyamines having at least two >N—H groups [monomers VI], g) optionallyone or more compounds having at least one alcoholic OH group and atleast one >N—H group [monomers VII] and h) optionally one or moremonohydric polyetheralcohols [monomers VIII], with the proviso that theamounts of the incorporated monomers I to VIII are such that the(—OH+>N—H)/NCO equivalent ratios for the incorporated monomersIII/monomers I+II are from 0.1 to 0.75, monomers IV/monomers I+II arefrom 0.2 to 0.8, monomers V/monomers I+II are from 0.05 to 0.5, monomersVI/monomers I+II are from 0 to 0.4, monomers VII/monomers I+II are from0 to 0.4, monomers VIII/monomers I+II are from 0 to 0.2, and those forthe sum of the monomers III to VIII/monomers (I+II) are from 0.80 to1.25, the total amount of monomers I and monomers II contains from 50 to100 mol % of monomers I, and from 50 to 2000 mmol of the carboxyl groupsof the incorporated monomers V, per kilogram of polyurethane A, arepresent in anionic form in the aqueous formulation, and the dispersedpolyurethane particles have a particle size from 2–15 μm, to a leather.3. The matt finished leather as claimed in claim 1, wherein the monomerI is selected from the group consisting of hexamethylene diisocyanate(HDI) and 4,4′-diisocyanatodicyclohexylmethane.
 4. The matt finishedleather as claimed in claim 1, wherein the total amount of monomers Iand II contains from more than 90, up to, and including, 100 mol % ofmonomers I.
 5. The matt finished leather as claimed in claim 1, whereinthe monomer V is selected from the group consisting of lactic acid,dimethylolpropionic acid, dimethylolbutyric acid, trimethylolaceticacid, hydroxypivalic acid and glucuronic acid.
 6. The matt finishedleather as claimed in claim 1, wherein the monomer V is selected fromthe group consisting of lactic acid and dimethylolpropionic acid.
 7. Thematt finished leather as claimed in claim 1, wherein the monomer V isdimethylolpropionic acid.
 8. The matt finished leather as claimed inclaim 1, wherein the monomer VI is selected from the group consisting ofethylenediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane and4,4′-di(aminocyclohexyl)methane.
 9. The matt finished leather as claimedin claim 1, wherein the monomer VI is 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane.
 10. The matt finished leather as claimed inclaim 1, wherein the >N—H/NCO equivalent ratio for the monomersVI/monomers (I+II) is from 0.02 to 0.4.
 11. The matt finished leather asclaimed in claim 1, wherein ammonium NH₄ ³⁰ is present as the oppositeion of the carboxyl groups of the incorporated monomers V.
 12. The mattfinished leather as claimed in claim 1, wherein the reaction of themonomers, is carried out in the absence of metal organyls.
 13. The mattfinished leather as claimed in claim 1, obtained by reacting themonomers in the presence of a cesium salt.
 14. The matt finished leatheras claimed in claim 3, wherein the total amount of monomers I and IIcontains from more than 90, up to, and including, 100 mol % of monomersI.
 15. The matt finished leather as claimed in claim 3, wherein themonomer V is selected from the group consisting of lactic acid,dimethylolpropionic acid, dimethylolbutyric acid, trimethylolaceticacid, hydroxypivalic acid and glucuronic acid.
 16. The matt finishedleather as claimed in claim 4, wherein the monomer V is selected fromthe group consisting of lactic acid, dimethylolpropionic acid,dimethylolbutyric acid, trimethylolacetic acid, hydroxypivalic acid andglucuronic acid.
 17. The matt finished leather as claimed in claim 3,wherein the monomer VI is selected from the group consisting ofethylenediamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane and4,4′-di(aminocyclohexyl)methane.
 18. The matt finished leather asclaimed in claim 5, wherein the monomer VI is selected from the groupconsisting of ethylenediamine,1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane and4,4′-di(aminocyclohexyl)methane.